This invention relates in general to magnetostatic wave resonators and relates more particularly to a method of manufacture that makes this resonator have improved properties and makes it suitable for batch processing. In prior devices, yttrium iron garnet (YIG) spheres and slabs have been used as resonators (See, for example, the articles J. D. Adam "Delay of Magnetostatic Surface Waves in Y.I.G. Slab", Electronics Letters, Vol. 6, No. 22 (1970) directed to resonance of YIG slabs; and J. P. Castera et al, "Magnetostatic Wave Resonators", Proc. of 1981 RADC, 218-228 (1981) directed to YIG thin film devices). In these devices, a pair of complex array reflectors are formed on the YIG film to reflect the magnetostatic waves generated in the film. These reflectors functionally act like the walls of a resonant cavity. This type of resonator requires a complex fabrication procedure and also exhibits a relatively high insertion loss and low Q.
In U.S. Pat. No. 4,528,529 entitled MAGNETOSTATIC WAVE RESONATORS, issued on July 9, 1985 to Ernst Huijer, another thin YIG film resonator is presented. In this resonator, a wafer saw is used to cut a thin block of YIG from a thin YIG film. Two sides of the block are substantially parallel so that the block acts as a resonator for magnetostatic waves reflecting between these two sides of the block. A pair of parallel microstrip transducers are formed on a substrate for use in coupling energy into and out of the block. The YIG block is then attached to the substrate in between these transducers by a nonconducting adhesive such as RTV manufactured by Dow. A microscope is used to assist in aligning the sides of the YIG block parallel to and midway between the parallel microstrip transducers. Such resonators can exhibit extremely high Q's and when their dimensions are optimized, can exhibit very low loss (.ltoreq.10 dB) over a very wide tuning range from 1-22 GHz (see the article K. W. Chang and W. Ishak, "Magnetostatic Forward Volume Wave Straight Edge Resonators", to appear in Proc. of IEEE-MTT Symposium, 1986). In order to suppress spurious modes, it is essential that the two sides that reflect the magnetostatic waves be parallel to a high degree of accuracy. This is a critical step and requires a very careful alignment procedure during the cutting operation and usually requires a technician to precisely align the saw relative to the film. This results in a time consuming procedure that is inherently variable in quality. It also requires that each of the block be cut individually. The formation of the two parallel sides by use of a saw usually produces chipping of these sides, resulting in performance degradation. It would be advantageous to have a resonator manufacturing process that produces a large number of blocks in a single iteration of the process, that produces flat reflective sides and that does not require human input in the critical steps of forming the two parallel sides and aligning transducers parallel to them.